I could structure you could structure he could structure we could structure you could structure they could structure
V-ing form
I could be structuring you could be structuring he could be structuring we could be structuring you could be structuring they could be structuring
Perfect
I could have structured you could have structured he could have structured we could have structured you could have structured they could have structured
V-ing perfect
I could have been structuring you could have been structuring he could have been structuring we could have been structuring you could have been structuring they could have been structuring
Negation
Simple form
I couldn't structure you couldn't structure he couldn't structure we couldn't structure you couldn't structure they couldn't structure
V-ing form
I couldn't be structuring you couldn't be structuring he couldn't be structuring we couldn't be structuring you couldn't be structuring they couldn't be structuring
Perfect
I couldn't have structured you couldn't have structured he couldn't have structured we couldn't have structured you couldn't have structured they couldn't have structured
V-ing perfect
I couldn't have been structuring you couldn't have been structuring he couldn't have been structuring we couldn't have been structuring you couldn't have been structuring they couldn't have been structuring
Interrogative form
Simple form
could I structure? could you structure? could he structure? could we structure? could you structure? could they structure?
V-ing form
could I be structuring? could you be structuring? could he be structuring? could we be structuring? could you be structuring? could they be structuring?
Perfect
could I have structured? could you have structured? could he have structured? could we have structured? could you have structured? could they have structured?
V-ing perfect
could I have been structuring? could you have been structuring? could he have been structuring? could we have been structuring? could you have been structuring? could they have been structuring?
Interro-negative form
Simple form
couldn't I structure? couldn't you structure? couldn't he structure? couldn't we structure? couldn't you structure? couldn't they structure?
V-ing form
couldn't I be structuring? couldn't you be structuring? couldn't he be structuring? couldn't we be structuring? couldn't you be structuring? couldn't they be structuring?
Perfect
couldn't I have structured? couldn't you have structured? couldn't he have structured? couldn't we have structured? couldn't you have structured? couldn't they have structured?
V-ing perfect
couldn't I have been structuring? couldn't you have been structuring? couldn't he have been structuring? couldn't we have been structuring? couldn't you have been structuring? couldn't they have been structuring?